9762 papers found
In the paper the paradigm of on-line (real-time) computation of parameters of a time series is developed. As an illustration the computation of the time deviation and Maximum Time Interval Error of the time error signal is shown.
The bird-cage method used for measuring cylindricity is reported to be the most effective, as it provides the most detailed information about an analyzed object. The average values of profiles measured with the cross-section and the generatrix methods may differ slightly, yet this may result from some design imperfections of the measurement instruments used. In this study, the problem of optimal profile matching is formulated and solved. As a result, the differences between the values of the registered profiles at the points of intersection of the scanning trajectories can be minimized.
According to International Recommendation OIML R 111, the weights of nominal values greater than 1 g may have a cylindrical shape with a lifting knob. Taking into account this kind of shape and that in the case of an automatic comparator, with the maximum capacity of 1 kg, the diameter of weighing pan is quite small for placing a group of weights from 500g to 100g, the subdivision method can’t be applied for the calibration of weights. By using the subdivision method presented in this paper, the cylindrical weights with a lifting knob, having nominal values from 500g to 100 g are calibrated...
The measurement of air shock wave pressure is a typical problem of transient measurement. Because the measurement data in many cases is used to judge the quality of a product, or as a basis for changes being made during a development phase, uncertainty analysis or assessment of measurement data takes a very important role in the process of reporting experimental results. It is very difficult or impossible for most transient measurements to be experimented repeatedly under the same condition, so their uncertainty analysis differs from the method of analyzing static measurement data. The paper...
Water is an essential good for human being necessity. It must be protected against pollution and useless leakage. Urban waterworks is a strategic infrastructure to be managed with particular attention and care so that users must be satisfied. Different techniques are used to detect leaks from waterworks, specifically from pipelines carrying water. Among them, spectral analysis is very interesting to apply amid problems related to the pipeline section. This paper presents an application of STFT (short-term Fourier transform) technique for identifying urban waterworks leaks; STFT technique is...
This paper presents the development of a controllable PMD (Polarization Mode Dispersion) source based on piezoelectric actuators as the element responsible for the birefringence variation. This device will be able to reproduce the PMD quantity in a controlled way in order to use it as a reliable metrological reference.
X-ray Computed Tomography (CT) is the latest innovation in manufacturing metrology as it offers several opportunities which are not possible with conventional tactile or optical measurement devices: The volumetric which is gained from a CT measurement represents – in contrast to other principles in manufacturing metrology – not only the surface but even the entire volume of the object which allows the analysis of conventionally not accessible features. Due to this fact current research work is concerned with the determination of the task-specific measurement uncertainty for CT measurements...
This article deals with the technical properties of fiber Bragg gratings with regard to their use as the strain-sensitive element in force transducers. Electrical strain gages are widely used in modern, precise force transducers. The electrical strain gage provides both outstanding technical properties and cost-effectiveness. Besides the electrical strain gage, the measurement principle of fiber Bragg-based sensors has recently become established. First applications in experimental mechanics have shown that this technology offers a lot of potential. Optical strain gauges are available on the...
The paper covers state of the art and latest development of piezoelectric motors at Kaunas University of Technology (Lithuania), that are related to the R&D of laser scanning and deflecting devices, measuring systems, nano-resolution positioning devices on the plane, various applications including teaching aids for Mechatronics studies and even "intelligent" toys. All presented motors are one- or multi-degree-of-freedom (multi DOF) resonant devices and generate continuous or step motion of the positioning object.
The precise measurement of ac voltage is traditionally performed by thermal converters. However, these devices are impractical outside the laboratories and the development of DACs and ADCs seems to provide a possibility for new high precision techniques. This paper investigates this problem and, by means of some experimental comparative tests, analyses these new possibilities.